Week 2: Embryology Flashcards
Mammalian brains are all quite ____.
similar
Provide some examples of mammals.
rats, mice, cats, primates
Most experimental studies of the brain are done on which type of mammals?
rodents (rats/ mice)
What are some key differences between the rat and human brain?
- convolutions (rat brain very small)
- size of cerebral hemispheres
For the mostpart, the CNS of humans has ________ symmetry, meaning what?
bilateral symmetry.
This means the left and right hand sides are mirror images of each other; which is true for both the brain and spinal chord (for the most part, variation exists to small degree)
Explain what is meant by the following general terms:
ipsilateral
structures which are on same side
ie. left eye is ipsilateral with left ear
Explain what is meant by the following general terms:
contralateral
structures are on opposite sides
ie. left eye and right eye
The whole of the CNS is derived from the walls of a ____ filled ____.
fluid filled tube
The neural tube starts forming from what day post conception?
17/18
What are the 3 primary germ layers?
endoderm
ectoderm
mesoderm
What does the ectoderm form?
- epidermis
- hair
- nails
- nervous system
What does the endoderm form?
-lining viscera (digestive, respiratory)
-
What does the mesoderm form?
- CT (bones)
- muscle
What are the alternative name(s) for the primitive nervous system? Why?
neuroectoderm
OR
neural plate.
The NS develops from the ectoderm, thus the NS primal form may be referred to as the neuroectoderm.
This primal form is essentially just a band of ectodermal tissue that gives rise to the NS. Thus it may also be referred to as a neural ‘plate’.
Explain what is meant by the following general term(s):
neural plate
- flat sheet of cells
- forms by day 18 of embryo development
- initiated by notochord
- forms all neurophil
Explain what is meant by the following general term(s):
neurophil
- neurons
- astrocytes
- oligodendrocyte
- ependymal cells
The neural plate develops a neural groove, in a process known as _______.
neurulation
Neurulation occurs by what day?
day 20
Where does the neural groove exist?
Within the midline of neural plate, on the posterior surface.
- (germ layer)
Endoderm
- (germ layer)
Mesoderm
- (germ layer)
Ectoderm
1
Future Neural Crest
2
Neural plate and groove
3
Ectoderm
4
Mesoderm
5
Notochordal plate
6
Endoderm
At what day of embrological development would you expect this to be? why?
Day 18. Because the neural groove has not formed yet, the germ layers are still “flat” rather than forming the proper tube structure that will occur in the following days.
At what day of embryological development would you expect this to be? why?
Day 20. Because neuralation has occured; you can clearly distinguish the neural groove but no somites are present yet.
At what day of embryological development would you expect this to be? why?
day 21. Neurelation has occured AND development of somites has begun.
2
Neural groove
4
Mesoderm
5
Notochord
6
Endoderm
2
Neural tube
3
Neural Crest
1
Ectoderm
2
Neural Fold
3
Mesoderm
5
Endoderm
A
Rostral
B
Caudal
1
Prosencephalon
2
Mesencephalon
3
Rhombencephalon
4
Spinal Cord
Explain what is going on in this image
Neural Crest cells are migrating from a rostral to caudal/lateral direction to eventually form the cell types for the:
- Sensory neurons in spinal & some cranial nerve ganglia (CN V, VII, VIII, IX, X)
- Postganglionic neurons of ANS
- Schwann cells of PNS
- Adrenal medulla
- Some cartilage, bone and connective tissue
- pigment cells
1
Spinal Cord
2
Myencephalon
3
Metencephalon
4
Mesencephalon
5
Diencephalon